Tape control arrangement for computer



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W5/v Ton E L. I//BBA RD By ArTo/P/vfy United States Patent O TAPE CONTROL ARRANGEMENT FOR COMPUTER Edward L. Vibbard, La Jolla, Calif., assignor to Bell Telephone Laboratories, Incorporated, N ew York, N. Y., a corporation of New York Original application December 17, 1946, Serial No. 716,827, now Patent No. 2,671,611, dated March 9, 1954. Divided and this application June 12, 1952, SerlalNo. 293,103

13 Claims. (Cl. 23S-61) This invention relates to calculators and particularly to electrical devices by which mathematical calculations may be carried out by the movement of simple electromagnetic means without the use of the gear trains, number wheels, cams or other such mechanical elements and is a division of application Serial No. 716,827, led on December 17, 1946, now Patent No. 2,671,611, granted March 9, 1954.

An object of the invention is to provide calculating means which will perform long and complicated operations in a minimum of time and with a minimum of apparatus.

The calculator in which the present invention is employed is known as a tape-controlled calculator adapted to perform extensive and complicated mechanical operations requiring such an intricate pattern of operations that its manipulation by hand in the manner of the old and familiar adding machines or other mechanical computers is possible but not practical. Hence the problems are planned and tapes are prepared which when put in the calculator will control the further automatic operation thereof for long periods of time, the results being calculated and then recorded in tabular form.

Operational orders, indices of standard and known information and problem data are recorded on various tapes in the form of perforations arranged in the various combinations of a permutation code similar to that employed in the printing telegraph art. In the operation of the calculator in which the present invention is employed a master or routine tape is provided to have general control of the sequence of operations of the calculator. The master control tape controls a complete cycle of calculating operations in accordance with a predetermined pattern in which there may be a great plurality of calculating cycles. The master control circuit issues orders each one of which upon completion terminates in the transmission to the master control circuit of a satisfaction signal which results in the advance of the routine or master tape and the transmission of the next order in sequence. The master or routine tape is in the form of an endless loop and normally or in the event of trouble, moves to an end-of-cycle position from which it advances to a new cycle.

An object of the present invention is the provision of a means to control the movement of an endless tape from any point reached during its movement to a given starting point in the least amount of time.

The calculator in which the present invention is employed is one in which the entry of every value is by way of a problem in multiplication. Addition is performed by entering an augend as a multiplicand with the automatic use of the digit one as a multiplier and thereafter entering one or more addends in the same manner, the addition becoming the result of an accumulation, a subtotal being produced upon the entry of each separate addend. Subtraction is performed in the same way as addition with the exception that the sign of the addend 2,782,985 Patented Feb. 26, 1957 ice (now the subtrahend) is changed. Division is performed by entering the dividend in the same manner as an augend, that is, entering the dividend as a multiplicand with the automatic use of the digit one as a multiplier. Thereafter, the divisor is entered as a multiplicand with the use of different trial quotient digits as multipliers, numerous trials of different digits being made automatically until certain given conditions are satisfied. It then being firmly establishedthat the entry of every problem is by way of an exercise in multiplication, it is to be understood that every calculation is actually an operation in addition. Multiplication consists in the addition of the tens andunits digits of the products of the multiplicand digits by a single multiplier digit with the registration of the sum in a storing register awaiting'accumulation with other such sums produced by successive multiplier` digits properly shifted.

The calculation therefore is straightforward in nature and differs from the conventional prior art methods in that counting means areeliminated. Thus in multiplication, if a multiplier digit of 5 is used, the process is not a five times counted repetition of the summing of the multiplicand but rather a single straightforward summing operation under a condition set by relays representing the multiplier digit 5. In division, while repeated trials of different quotient digits are made the trials are not counted but only the nature of the result is noted so that when the remainder (the divisor times the trial quotient digit being used as a subtrahend and the dividend being used as a minuend) changes from a negative to a positive number the quotient digit used in that trial is recorded. `What might be termed the approach from above, meaning the successive trials of lower values as quotient digits, eliminates both counting and recording of any information on unsuccessful trials.

One of the features of the calculating device though not claimed as a novel feature in this application is the means for stopping a calculation and giving an alarm when a difficulty is encountered coupled with timing means which if the diculty is not remedied within a predetermined period will cause the calculation to be abandoned and another started.

One necessary step instarting a new calculation is to move the master index 'to its starting point. Since for a complicated problem this master index, which is in the form of an endless loop, may be of considerable length, means are provided to move it from the point reached to the beginning either by continuing its forward movement or reversing the direction of movement and running it back to the beginning. For this purpose, a special indicium is recorded midway in the tape and a device which will determine the direction of its movement, if and when it is to be returned quickly to the beginning, is operated. Then, if the mid-point has been passed it is obviously quicker to move the tape forwardly but if this mid-point has not yet been reached, it is by the same token obviously quicker to reverse the direction of movement and to move the tape backwardly. A feature of the invention is therefore a means to control the movement of an endless tape from any point reached to a given starting point in the direction of the shortest distance between such points.

The drawings consist of seventeen sheets having twentytwo figures, as follows:

Fig. 1 and Fig. 2 taken together with Fig. 1 placed above Fig. 2 is a -ow chart indicating the manner in which the device of the present invention is operated;

Fig. 3 is a schematic circuit diagram showing certain details of the steering circuit and illustrating how this steering circuit determines which of the two storage registers shall be used asA the depository of a sum of the quantities expressed in the addend and augend registers;

Fig. 4 is a schematic circuit diagram showing the essential elements used for carrying out the calculating cycle, which diagram may be used in conjunction with Fig. 15 to explain in detail the steps in a calculating cycle;

Fig. 5 is a schematic circuit diagram showing the fundamental conception of the means for producing a recycle operation in the steering chain in a problem in division;

Fig. 6 is a schematic circuit diagram'used to explain ge general operations in the calculation of a quotient 'sin Fig. 7 is a sequence chart showing the advance 0f the steering chain relays during the calculation of a quotient of 74,593;

Fig. 8 is a block diagram showing how Figs. 9 to 14, inclusive, may be placed to form a circuit diagram, in which:

Figs. 9 and 10 show certain vcircuit details of the steering chain used in every calculating operation and has in addition a schematic representation of the master control circuit from which an operation in division is ordered, together with a schematic circuit representation of the Z register in which the quotient digts are registered as they are calculated;

Fig. 11 is a circuit diagram of the division steering circuit which controls the application of the various trial quotient digits; l

Figs. 12 and 13 show certain circuit details ofthe division auxiliary steering chain relay circuits;

Fig. 14 is a schematic circuit drawing showing the various parts of the common calculator in order to explain its operation during an operation in division under control of the circuits of Figs. 9 to 13;

Fig. 15 is a sequence chart showing the order in which the various steps of the calculating cycle are performed and is placed on a time basis even though each operation is in consequence of a previous operation land no time elements other than the time which it takes a relay to operate are involved;

Fig. 16 is a block diagram showing how Figs, 17, 18 and 19 may be placed to form a schematic circuit diagram to illustrate the operations when the device is recycled and particularly how the master tape is returned to its starting point over the shortest route, in which:

Fig. 17 shows a schematic representation of a tape transmitter;

Figs. 17 and 19 show the recycle circuits;

Fig. 18 shows the tens and units relays operated by the transmitter and indicates the code relays whereby any one of one hundred code leads may be selected by a two-digit code;

Fig. 2O is a circuit diagram showing in highly schematic form the condition of two control circuits within the steering chain when all relays thereof are in normal position;

Fig. 21 is a similar circuit showing the condition of these two circuits when a single steering relay has been operated; and

Fig. 22 is a similar circuit showing the condition of these two circuits when two steering relays are operated simultaneously.

This application is a division of said Vibbard applica-V tion which is one of a group of seven applications all based on the same arrangement. The Andrews-Vibbard application is a full and complete disclosure and includes a disclosure of the present invention, the other applications including the present divisional application and its copending parent application being abbreviated'disclosures of certain features of the complete device, as follows:

J. P. Juny .Cesareo-Stricklcr.

Filing date Applicant Serial Subject number Automatic Calculator.

Testing System, now

Patent l\o. 2,692,728, granted October 26, 1954.

Switching Control System, now Patent No. 2,665,578, granted January 19, 1954.

Automatic Code Translating System, now Patent No. 2,625,328, granted January Dec. 17, 1946 Dec. 17, 1946 716, 7e3 Dec. 17,1946

O. Cesareo 716, 753 17, 1946 Calculator Sign Control Circuit, now Patent No. 2,679,977, granted June l, 1954.

Automatic Calculator, now Patent No. 2,692,082, granted October 19, 1954.

E. G. Andrews 716, 762 17, 1945 The device in which the present invention is incorporated is a calculator operated by electrical circuit change in which each new circuit operation is dependent upon the successful completion of a previous operation. It consists essentially of a calculating arrangement, a plurality of tape transmitters of the kind commonly used in printing telegraph operation for entering both operational orders and mathematical information, a plurality of registers in which mathematical information from the tapes or calculated by the calculator may be stored temporarily and a printing device also of the type commonly used in the printing telegraph art for recording various items of information, including the arguments of the problems, partial results and the nal solutions.

In Fig. l there is shown a master control tape transmitter 101 which is used to transmit operational orders from a so-callcd routine tape into the master control circuit 106 which has general control over all the operations of the device. Other similar transmitters are the interpolator tape transmitter 102, the ballistic data tape transmitters 103 and 104 and the problem data tape transmitter 10S, each with its control circuit. All of these transmit mathematical information from appropriate tapes and all of this information is generically problem data. That provided by the problem data tape constitutes the arguments of the problem, that from the interpolator tape constitutes correlated or empirical data and that from the ballistic tapes constitutes table information or precalculated data such as is usually found in the soecalled tables of functions such as trigonometric, logarithmic, ballistic and other such data. In the operation of this device the routine tape is operated cyclically, that is, it runs through its transmitter over one complete set of routine orders necessary for the calculation of a function from one given argument or set of arguments. The problem data tape usually contains a series of arguments and is moved forwardly step-by-step under control of the master control circuit, the master tape operating through one cycle for each argument. The remaining tapes con tain necessary information and may be moved from point to point either forwardly or backwardly to transmit information called for yby the master control from time to time during the calculating operations.

The calculator here generally shown as included in the broken line rectangle 116, consists primarily of four re` lay registers, the A register 12S constituting an augend element, the B register 129 constituting an addend ele* ment and the C register and D register 130 being used alternatively as sum elements. All problems presented to the -calculator are in the form of problems in multiplication and the calculation is actually performed by :summing lthe values registered at various times in the A and B registers. For this purpose a set of multiplying relays 127 and a set of multiplier relays 133 are provided, by means of which a multiplicand operating the multiplying relays 127 may be multiplied by one digit at a time of the multiplier which operates the multiplier relays 133. There is provided a set of switching relays 131 for determining into which register, the C register 125 or the D register 1.30 the values in the A and B registers shall be summed. Values stored in the D register 130 may be transferred only to the B register 129, by way of an inverter 132. This is a means by which the value being transferred from the D register to the B register may be transferred as it is or in its complemental form. Values stored in the C register 125 may be transferred either to the A register or transmitted out over the C multiple 117 for transfer to any one of the various registers shown in Fig. 2.

The calculator 116 is under general control of a steering circuit 121 which controls the various steps in a multiplying calculation cycle. When a problem in division is presented an additional circuit, the division steering circuit 122 is brought into action to make the necessary changes and alterations in the calculating cycle. The cut-in relays 120 ordered into operation by the master control circuit 106 through the code distributing relays 108 operate to activate one decimal denominational order at a time of certain registers which then transmit over the R multiple 115 to operate the multiplier relays under control of the steering circuit 121. The division steering circuit, ordered into operation over the path 124, besides modifying the calculation cycle provides a supply of multiplier digits over the R multiple 115 to the multiplier relays 133 as trial quotient digits and transmits the correctly calculated quotient digits over the C multiple 1,17.

The steering circuit essentially constitutes the means for controlling the pattern of operations throughout the calculation cycle. Since in problems in multiplication this cycle is straightforward the steering circuit comprises a string of relays which operate in sequence starting from any given selected point and ending at any given selected point, there being in this embodiment three relays for each cycle and as many groups of three as there will be cycles or shifts in columnar arrangement. In a problem in division it is not possible to select the true quotient digit without trial and hence if a certain digit is tried and found to be unsatisfactory the orderly sequence in the operation of the steering relays must be interrupted and the chain recycled, that is after such an unsatisfactory trial the steering chain must be reentered and another trial made. Hence the division steering circuit 122 is shown as a separate entity but one which operates in conjunction with the multiplying circuit 121. Actually it operates in addition to the principal circuit 121.

Fig. 3 is a schematic circuit diagram having some of the attributes of a ilow chart intended to illustrate the transfer of values between the different registers of the common adder. The so-called start function relays and the end function relays as well as a number of the steering chain relays are shown. The start function and end function relays are selectively operated under orders from the master control circuit and thus determine at what point the action of the steering chain shall start and at what point it shall terminate. The four registers of the common adder are each indicated by a rectangle appropriately labeled.

Relays 301 to 305 are the start function relays and relays 306 to 309 are the end function relays. Every calculation requires that one of each set be energized to define the limits of the operation as fully explained in the Andrews-Vibbard application. Now it will be remembered that the values held in the A (augend) register 310 and the B (addend) register 311 may be summed into either the C register 312 or the D register 313. For this purpose a group of relays here represented by the AC relay 314 and the AD relay 315 is employed. When the AC relays are operated, the sum of the values in the A register 310 and the 'B register 311 is registered in the C register 312 and when the AD relays are Voperated the sum is registered in the D register 313. This arrangement is clearly indicated by the circuits through the armatures and contacts of the AC and AD relays.

Summing is accomplished by grounding the carry-in lead 316 (and supplying certain local grounds to the summing circuits) whereby the combination circuits set up through the B register 311 and the A register 310 are effective to Vrtigister a sum in either the C or D register.

All operations of the adder are controlled by the steering chain which as pointed out is generally controlled by the start and end function relays. Thus if the S-S start function relay 301 has been operated by the master control circuit, the relay 317 will be the irst in the steering chain to operate and the chain start ground lead 318 will be extended through the armature and contact of relay 301 to the AC lead 319 to operate the AC relays 314. The A and B registers being set by the multiplying and multiplier relays and the CO/NO lead 320 being open at this time (since no number 1 chain relay is up) so that neither the complement relay 321 nor the normal relay 322 may be operated through the contacts of either the NEG relay 323 or the POS relay 324, whichever is operated, the carry lead 316 may be grounded. Hence the sum of the values in the A and B registers is registered in the C register 312.

If, on the other hand, the 1-S start function relay 302 has been operated by the master control circuit, then the 1S-1 steering chain relay 325 will be the first to operate and the AD lead 326 will be grounded instead of the AC lead 319. Hence the relay 315 instead of the AC relay 314 will be operated and the sum will be registered in the D register.

Now it will be explained in more detail hereinafter how, after the D register has been filled, the next step consists in transferring the value in the C register to the A registr and that in the D register to the B register. Hence on the operation controlled by any one of the number 2 relays, such as the 1S-2 relay 327, the SI1-2 relay 328 or the S1f2 relay 329, the CO/NO lead 320 is grounded thus operating either the NO relay 322 to transfer the registration in the D register 313 in normal manner to the B register 311 or operating the CO relay 321 to invert the value being transferred from the D register to the B register. During this operation neither the AC nor AD relays are operated and since either the CO or the NO relay is operated, the carry-in lead is opened.

However, as soon as one of the number 3 relays such as 1S-3 relay 330, S0-3 relay 331 or S1-3 relay 332 is operated, then the AC lead 319 will be closed so that the sum of the values transferred from the C and D registers will be calculated and registered in the C register. The CO/NO lead 320 is opened during the operation of the number 3 relay alone so that the carry-in lead 316 may be closed.

These operations may be followed more closely through the following description of the details of the calculating cycle.

Fig. 4 is a schematic circuit diagram useful in explaining the calculating cycle. As explained hereinbefore, every problem is entered in the calculator as a problem in multiplication and solved by an operation in addition. The calculating cycle, after the proper conditions have been set up by the master control circuit, consists in the interaction of circuits controlled by the common adder and by the steering chain. These are three fundamental circuits associated with the common adder known as the locking circuit, the down-check circuit and the up-checl; circuit. The locking circuit is one divided into four branches one for each of the four registers A, B, C 

